Your title, Bebe, reminded me of an experience with my late MiL when she was diagnosed with uterine cancer and had gone through chemo treatment, which made her feel so awful that she gave it up. She got very depressed at one point because her doctor had told her she would get better; and she wasn't, she complained. Which surprised me, because, compared to the depths of the chemo regimen, she was much less nauseous and more alert; to me, that was "better." Talking to her, I determined our definitions were different — my "better" was "better than she had been before," while her "better" was "back to how she had been before the diagnosis." (I point the finger at my mother, the RN — in our house growing up, "better" and "well" were two separate and distinct terms.)

Reading your story, of course, your sister's doctor meant that she was never going to get well (recover) or improve (get better than she was post-stroke).